Field of the Invention
The present invention relates to a system and a method for controlling a brake of an electric vehicle. More particularly, the present invention relates to a system and a method for controlling a brake of an electric vehicle including a smart cruise control system that prevent a loss of braking force caused by the smart cruise control system.
Description of Related Art
Generally, environmentally friendly vehicles such as an electric vehicle, a fuel cell vehicle, and a hybrid electric vehicle are operated by a driving motor which generates torque by electrical energy.
The electric vehicle only uses power of the driving motor operated by power of a battery, and on the contrary, the hybrid electric vehicle uses power of an internal combustion engine and power of the driving motor by efficiently combining them.
The motor of the electric vehicle operates as a generator during braking, and converts kinetic energy to electrical energy. The converted electrical energy is charged in a battery. As such, a system that simultaneously implements reduction of kinetic energy and generation of electrical energy is defined as a regenerative braking system.
Meanwhile, a smart cruise control (SCC) system is gradually being used for a vehicle in recent years. The smart cruise control system can perform acceleration and deceleration and maintain an appropriate vehicular distance from a preceding vehicle by automatically controlling a throttle valve, a brake, and a transmission of the vehicle.
If a driver steps on a brake pedal for braking when the smart cruise control system is operated and braking force caused by the smart cruise control system is generated, the smart cruise control system is stopped and additional braking force is generated. At this time, the smart cruise control system of an engine vehicle increases hydraulic pressure to generate braking force, thereby a stroke of the brake pedal is increased. Thus, if the driver steps on the brake pedal for braking, braking force caused by the smart cruise control system is maintained.
However, the smart cruise control system of the electric vehicle generates braking force by regenerative braking for fuel efficiency since the hydraulic pressure braking and the regenerative braking are separately performed in the electric vehicle. Therefore, in the electric vehicle, a position value of the brake pedal is 0% even though braking force caused by the smart cruise control system is generated, such that a loss of braking force may occur compared to the engine vehicle.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.